Synonyms: 2H-Dipyridazino[1,6-d:1',6'-g]pyrrolo[1,2-m][1,4,7,10,13,16]oxapentaazacyclooctadecine,cyclic peptide deriv.; D-Valine, N-[1-[N-[[2-[[D-hexahydro-2-(L-2-hydroxy-3-methyl-1-oxobutyl)-3-pyridazinyl]carbonyl]-L-hexahydro-cis-5-hydroxy-3-pyridazinyl]carbonyl]-N-methyl-D-leucyl]-trans-4-methyl-L-prolyl]-,p-lactone;N-[1-[N-[[2-[[D-Hexahydro-2-(L-2-hydroxy-3-methyl-1-oxobutyl)-3-pyridazinyl]carbonyl]-L-hexahydro-cis-5-hydroxy-3-pyridazinyl]carbonyl]-N-methyl-D-leucyl]-trans-4-methyl-L-prolyl]-D-valinep-lactone